Re: Particle biasing

Dear Stefan and Alfredo,

Now I made a very simple geometry: 1 MeV isotropic photon source in
lead. And used a specific usimbs.f which makes the photon split (fimp=2)
when it passes the 1 cm radius, but only when the z coordinate is positive.
A scored the photon flux from -20 to 20 cm in every direction.

The result should be: The same fluxes for the similar places in the
positive and negative z halfspace, but with different errors.

But the simulation gave that the fluxes differ, in the pozitive z
halfspace I got higher fluxes than in the negative halfspace
(see attached picture in usimbs.zip)

So the error should be in Fluka, maybe it gives wrong weights for the
splitted particles?

Can you check the results with Fluka 2006.3b? I already changed to 2008.3.2.

Cheers,
David